Systems for printing can include droplet ejection devices such as ink jet printers. Ink jet printers typically include one or more printheads. Conventionally, a printhead includes a reservoir and a jetting assembly. The reservoir supplies ink to the jetting assembly, which includes a jetting module that ejects ink droplets as required. In some embodiments, jetting modules each include multiple ink paths that lead from an ink supply to a corresponding orifice path. Each orifice path terminates in a orifice opening from which ink drops are ejected. Ink drop ejection is controlled by pressurizing ink in the ink path with an actuator, which may be, for example, a piezoelectric deflector, a thermal bubble jet generator, or an electro statically deflected element.
Drop ejection from each orifice opening can be independently controlled. In a drop-on-demand printhead, each actuator is fired to selectively eject a drop at a specific pixel location of an image as the jetting assembly and a printing substrate are moved relative to one another. In high performance jetting assemblies, the orifice openings typically have a diameter of about 50 microns or less, e.g., about 25 microns, are separated at a pitch of about 100-300 orifices/inch, have a resolution of about 100 to about 3000 dpi or more, and provide drop sizes of about 1 to about 70 picoliters (pl) or less. Drop ejection frequency is typically about 10 KHz or more.
Hoisington et al. U.S. Pat. No. 5,265,315, the entire contents of which is hereby incorporated by reference, describes a jetting module having a semiconductor body and a piezoelectric actuator. The module body is made of silicon, which is etched to define ink chambers. Orifice openings are defined by a separate orifice plate, which is attached to the silicon body. The piezoelectric actuator has a layer of piezoelectric material, which changes geometry, or bends, in response to an applied voltage. The bending of the piezoelectric layer pressurizes ink in a pumping chamber located along the ink path.
Further examples of jetting modules are disclosed in U.S. patent application Ser. No. 10/189,947, entitled “PRINTHEAD,” to Andreas Bibl et al., filed on Jul. 3, 2002, the entire contents of which are hereby incorporated by reference.
In general, printheads can include one or more jetting assemblies. Printing systems can print in a single pass of the substrate relative to the printhead, or in multiple passes. Printheads can be used to jet inks and/or other fluids, such as materials used for electronic components (e.g., electrically conductive materials) or color filter materials for flat panel displays, for example.